JP2021107165A - Work vehicle - Google Patents

Abstract

To provide a work vehicle which an operator can stop without having discomfort.SOLUTION: A work vehicle comprises: a travel control part 43 which controls an operation cylinder 24 making speed change by operating a trunnion shaft 23 of a hydrostatic infinite variable-speed drive 10 which transmits by making speed change relative to rotation power of an engine E; left and right brake pedals 13L, 13R which operate respective left and right brake devices 32L, 32R; a pedal connection part 33 which connects the left and right brake pedals 13L, 13R; a connection sensor 38b which detects whether the pedal connection part 33 is in connection state or non-connection state; and a brake pedal sensor 50 which detects operation of either of left and right brake pedals 13. The travel control part 43 decelerates and controls the operation cylinder 24 based upon stepping amount of the brake pedals after the brake pedal sensor 50 detects the operation of either of the left or right brake pedals 13 when the connection sensor 38b detects the connection state.SELECTED DRAWING: Figure 14

Description

The present invention relates to a work vehicle.

In a work vehicle equipped with a hydraulic stepless speed change device, in a work vehicle equipped with a hydraulic stepless speed change device, a sub-shift operation detection means for detecting the operation of the sub-transmission device is provided, and independent braking devices are operated on the left and right sides. The left and right brake pedals and the left and right brake pedals are switched between the connected state and the unconnected state. The brake pedal connection part is operated. The brake connection operation locking means is provided, the lock state detection means for detecting the lock state of the brake connection release operation tool is provided, the lock state detection means detects the unlock state, and the auxiliary shift operation detection means operates at a high speed position. The control unit is known to have a technique of setting the traveling regulation mode in which the tranion shaft is held in the neutral position (see, for example, Patent Document 1).

JP-A-2017-115901

However, since the hydraulic continuously variable transmission produces a braking effect during deceleration, a shock may occur if the continuously variable transmission is suddenly changed, and the driver may feel uncomfortable.

An object of the present invention is to provide a work vehicle in which a driver can stop without discomfort in view of such conventional problems.

In order to solve the above-mentioned problems and achieve the object, the work vehicle according to one aspect of the embodiment includes an engine, a hydrostatic stepless speed change device that shifts and transmits the rotational power of the engine, and the hydrostatic non-hydraulic device. A travel control unit that controls the operation cylinder that operates the tranion shaft of the speed change device to shift gears, left and right braking devices that brake the left and right drive wheels, and left and right brake pedals that operate the left and right braking devices, respectively. , A pedal connecting portion that connects the left and right brake pedals, a connecting sensor that detects whether the pedal connecting portion is in a connected state or a non-connected state, and a brake that detects the operation of either the left or right brake pedal. When the brake pedal sensor detects the operation of either the left or right brake pedal when the connection sensor is provided with a pedal sensor and the connection sensor detects the connection state, the traveling control unit uses the operation cylinder as the amount of depression of the brake pedal. It is characterized in that deceleration control is performed based on the above.

According to one aspect of the embodiment, the driver can stop without discomfort.

Side view of the tractor of this embodiment Same as above Top view of the main part Same as above Top view of the main part Same as above Top view of the main part Diagram of tractor power transmission Cross section of HST (A), (b) and (c) are side views showing the actions of the HST and the operating cylinder. Perspective view of the main part of the tractor operation unit Same as above, perspective view of the main part Same as above Side view of the main part Side view of the brake pedal (A) and (B) are side views showing the locked and unlocked states of the brake connection release operating tool. Side view of main shifting lever Control block diagram Perspective view of lock lever resin cover Same as above Rear view of the main part Top view of lock lever Same as above side view

An embodiment of the work vehicle of the present invention will be described with reference to the drawings.

FIGS. 1, 2 and 3 show a tractor as an example of the work vehicle of the present invention. The tractor T has an engine E mounted inside a bonnet 1 at the front of the vehicle body, and the rotational power of the engine E. Is transmitted to the transmission in the mission case 2 via the hydrostatic continuously variable transmission (HST) 10, and the rotational power decelerated by this transmission is transmitted to the front wheels 3 and the rear wheels 4. A steering wheel 5 for steering the front wheels 3 and 3 is installed behind the engine E, and a driver's seat 6 is installed behind the steering wheel 5. A hydraulic cylinder case 7 is mounted on the rear upper part of the mission case 2, and lift arms 8 and 8 forming a part of the hydraulic lifting mechanism are rotatably pivotally supported on both left and right sides of the cylinder case 7. Has been done. When hydraulic oil is supplied to the work machine lifting hydraulic cylinder 9 housed in the cylinder case 7, the lift arms 8 and 8 rotate upward, and when discharged, the lift arms 8 and 8 descend. A working machine such as a rotary tiller is attached to the rear part of the vehicle body via a three-point link mechanism consisting of a top link, a lift rod, a lower link, and the like.

Further, a clutch pedal 12 is arranged on the left side of the dashboard cover 9 and the operation column 11, and brake pedals 13L and 13R are arranged on the right side to brake the left and right traveling brakes (left and right rear wheels 4, 4) of the vehicle by depressing operation. It is provided so as to project upward from the step floor. The brake pedals 13L and 13R are configured so that the brake pedal shaft 14 mounted on the lower side of the step floor in the left-right lateral direction can be stepped on as a rotation fulcrum. 14L is a left brake rod and 14R is a right brake rod.

A forward / backward lever 15 that controls the forward movement and reverse movement of the vehicle is arranged on the left side of the operation column 11, and an accelerator lever 16a and an accelerator pedal 16b are arranged on the right side of the operation column and near the brake pedals 13L and 13R.

Further, a main shift lever 17, an auxiliary shift lever 18, a PTO shift lever 19, and the like are arranged on the left side of the driver's seat 6.

The hydrostatic stepless transmission (HST) 10 is composed of a variable displacement hydraulic pump 20 and a fixed capacitance hydraulic motor 21, composed of a variable pump swash plate 22a and a fixed motor swash plate 22b, and a hydraulic pump. By changing the inclination of the swash plate 22a of 20, the rotation of the hydraulic motor 21 is changed. That is, by changing the angle of the swash plate 22a of the pump, the capacity of the pump changes and the rotation speed of the motor 21 changes. When the angle of the swash plate 22a is perpendicular to the axis, the capacity of the motor becomes zero, and the motor does not rotate (neutral state). As the pump rotates with the shaft, each piston slides on the surface of the swash plate 22a, and hydraulic oil is sent to the motor.

The rotation angle of the tranny shaft 23 to which the swash plate 22a is fixed is changed by the operation cylinder 24 as an actuator that operates by detecting the movement of the main shift lever 17 by the main shift sensor 29, and the traveling system output of the hydraulic motor 21 is changed. The rotation of the shaft 25 is changed, and the front and rear wheels are changed via the auxiliary transmission 28.

The hydraulic pump 20 is input from the engine via the input shaft 26, and is output from the output shaft 27 to the PTO shaft 30.

Further, in the example shown in FIG. 7, the neutral cam 46 is fixed to the trunnion shaft 23, and when the roller 47 falls into the recess 46a of the neutral cam, the trunnion shaft returns to the neutral position (N) (FIG. 7). See (b)). Note that FIG. 7 (a) shows a forward (F) state, and FIG. 7 (c) shows a reverse (R) state. This is done by operating the main shift lever 17.

FIG. 11 is a side view of the brake pedal. Since the brake pedal sensor 50 claw is rotated by the pin 13p attached to the arm of the left brake pedal 13L, the brake pedal sensor 50, which is a potentiometer, can detect the stepping position of the left brake pedal 13L. This brake pedal sensor may detect the depressed position of the right brake pedal 13R.

The auxiliary transmission 28 is interlocked with the output shaft 25 of the hydraulic motor 21, transmits power by meshing gears, switches to three speeds of high speed H, medium speed M, and low speed L, and drives the front and rear wheels 3 and 4. It is continuously connected to the above, and the switching operation is performed by the auxiliary shift lever 18.

An auxiliary transmission sensor 31 is provided as an auxiliary transmission operation detecting means for detecting the position of the auxiliary transmission lever 18 that operates the auxiliary transmission device 28.

The left and right independent braking devices 32L and 32R are controlled by the left brake solenoid 32Lso and the right brake solenoid 32Rso, and the left and right brake pedals are connected to the right brake pedal 13R and the left brake pedal 13L that operate the left and right brakes, respectively. Alternatively, a connecting operation tool 34 for operating the brake pedal connecting portion 33 to be disconnected via the disconnecting wire 36 is provided. The brake pedal connecting portion 33 always urges the left and right brake pedals to the connecting side by a connecting spring 39.

A brake connection lock lever 37 is provided as a brake connection operation locking means for locking or unlocking the operation of the connection operation tool 34 via the lock rod 35 and the lock plate 40 (see FIG. 8). When the brake connection lock lever 37 is operated downward as shown in FIG. 12 (A), the lock plate 40 rotates clockwise as shown through the lock rod 35, and when the position is in contact with the lock pin 41, the connection operation tool is used. The first projecting piece 42a of 34 comes into contact with the lock plate 40 and is in a locked state so that the stepping operation cannot be performed. When the brake connecting lock lever 37 is operated upward as shown in FIG. 12B, the first projecting piece 42a of the connecting operating tool 34 is separated from the lock plate 40 and is in an unlocked state in which the stepping operation is possible.

A second projecting piece 42b is provided on the connecting operation tool 34 side, and when this acts on the connecting sensor 38b, the traveling control unit 43 detects a signal and recognizes that the brake pedal connecting unit 33 is in the connected state. .. Further, if the second projecting piece 42b does not act on the connection sensor 38b, the traveling control unit 43 recognizes that the brake pedal connection unit 33 is in the unconnected state.

A third projecting piece 42c is provided on the rotating shaft of the lock plate 40, and when it acts on the lock sensor 38a, the traveling control unit 43 detects a signal and the connecting operation tool 34 is in an unlocked state in which the connecting operation tool 34 can be stepped on. Recognize that. Further, if the third projecting piece 42c does not act on the lock sensor 38a, the traveling control unit 43 recognizes that the connecting operation tool 34 is in a locked state in which the stepping operation cannot be performed.

When the unlocked state is detected by the connection sensor 38b and it is detected that the auxiliary transmission sensor 31 which is the auxiliary transmission operation detection means is operated to the high speed position H, the traveling control unit 43 positions the trunnion shaft 23 of the HST in the neutral position. It is set to the traveling regulation mode U to return to. In such a situation, it is convenient to sound a warning buzzer to prompt the operator to connect the left and right brake pedals.

FIG. 14 is a control block diagram of the tractor according to the embodiment. The travel control unit includes a detection value of the amount of depression of the left brake pedal 13L from the brake pedal sensor 50, a detection value of whether the brake pedal connecting portion 33 is connected or not connected from the connecting sensor 38b, and a lock sensor 38a. The detection value of whether the connection operation tool 34 is in the unlocked state where the connection release operation is possible or the lock state where the connection release operation is impossible is input.

Further, the vehicle speed sensor 54 detects the number of rotations related to the rear wheels 4, which are the driving wheels, the main shift sensor 29 determines the position of the main shift lever 17, and the auxiliary shift sensor 31 determines the position of the sub-main shift lever 18. The GPS unit 51 inputs the positioning information, and the steering angle sensor 52 inputs the detected value of the steering angle.

Further, depending on the input value of the travel mode selection switch 61, the travel control unit 43 applies various control settings suitable for road travel, such as road travel mode D, and work travel mode W to which various control settings suitable for work travel are applied. Switch the driving mode. Further, a detection value based on the operation of the accelerator pedal 16b is input from the accelerator pedal sensor 62, and a detection value based on the operation of the accelerator lever 16a is input from the accelerator lever sensor 63.

The travel control unit 43 adjusts the current value output to the forward side solenoid 48 and the reverse side solenoid 49, and operates the trunnion shaft operation cylinder 24 at an arbitrary position. Further, the output values for the right brake solenoid 32Rso and the left brake solenoid 32Lso that operate the left and right braking devices 32R and 32L are adjusted to generate an arbitrary braking force.

Further, the traveling control unit 43 can transmit an engine speed instruction value to the engine control unit 44 to adjust the engine speed to an arbitrary value. For example, when the driving mode is the road driving mode D, the smaller of the indicated value of the engine speed based on the detected value of the accelerator pedal sensor 62 and the indicated value of the engine speed based on the detected value of the accelerator lever sensor 63 is smaller. Is transmitted to the engine control unit 44, and when the driving mode is the working driving mode W, the engine speed is indicated based on the detection value of the accelerator pedal sensor 62 and the engine is based on the detection value of the accelerator lever sensor 63. Of the indicated values of the number of revolutions, the larger indicated value is transmitted to the engine control unit 44.

If the accelerator lever 16a is forgotten to be returned while driving on the road, the engine speed may not decrease and the vehicle may not decelerate even if the accelerator pedal 16b is released. However, according to the above configuration, the vehicle always decelerates when the accelerator pedal 16b is released. Therefore, it is possible to drive safely on the road. In addition, when working while keeping the engine speed constant by the accelerator lever 16a during work running, if a temporary shortage of torque is felt, the engine speed can be increased by depressing the accelerator pedal 16b. can.

Since such control is operated by a program incorporated in the travel control device 43, by rewriting the program, on the contrary, the larger indicated value is adopted in the road travel mode D, or in the work travel mode W. The smaller indicated value can be adopted, the accelerator lever 16a can be disabled in the road driving mode D, and the accelerator pedal 16b can be disabled in the working driving mode W. Further, instead of rewriting the above-mentioned program, the program may be written in advance and the setting may be switched by a dial type switch, a tablet or the like.

When the connection sensor 38b detects the connection state of the left and right brake pedals 13L and 13R, the travel control unit 43 detects that the brake pedal 13 is depressed by the brake pedal sensor 50, and the engine rotates based on the depression amount. Change the number. Discount the indicated value of the engine speed according to the ratio of the depression amount from the position slightly depressed from the release position where the depression amount of the brake pedal 13 is the minimum (zero) to the position slightly before the depression amount is the maximum. The idling speed is reached at a position slightly before the maximum amount of depression.

As a result, even if the power transmission is not neutral when the brake is depressed for some reason, the engine speed is reduced, so that the vehicle can be reliably stopped without being dragged.

In the above configuration, the connection sensor 38b detects the connection state of the left and right brake pedals 13L and 13R, but detects the connection state of the left and right brake pedals 13L and 13R according to the depression of the brake pedal 13. By setting the condition of the engine speed reduction control, it is possible to run without lowering the engine speed during work running with one brake operation, but instead of the connection sensor 38b, the detection state of the lock sensor 38a is set to the engine speed. It may be a condition for number reduction control.

Specifically, when the lock sensor 38a detects the locked state of the connecting operation tool 34, that is, when the connection between the left and right brake pedals 13L and 13R cannot be released, the brake pedal 13 by the brake pedal sensor 50 When the stepping is detected, the same effect can be obtained even if the engine speed is changed based on the stepping amount.

Further, the trunnion shaft operating cylinder 24 may be decelerated according to the detected value of the brake pedal sensor 50. Specifically, the trunnion shaft operating cylinder 24 is depressed according to the ratio of the depression amount from the position slightly depressed from the release position where the depression amount of the brake pedal 13 is the minimum (zero) to the position slightly before the depression amount is the maximum. It is controlled so that the indicated value for is discounted, and it becomes a neutral state at a position slightly before the maximum amount of depression.

As a result, it is possible to prevent the vehicle from being dragged when the brake pedal 13 is depressed. Further, since the hydrostatic continuously variable transmission 10 produces a braking effect when the speed is changed to the deceleration side,
By decelerating according to the amount of depression of the brake pedal 13, it is possible to stop naturally.

The solenoid shaft operation detecting means for detecting the operation on the solenoid shaft 23, that is, the main shifting lever 17, detects the position of the lever 17 by the main shifting sensor 29 and sends it to the traveling control unit 43, and the traveling control unit 43 thereof. The state in which the current flowing through the forward solenoid 48 and the reverse solenoid 49 is adjusted according to the detected value to operate the tranny shaft, and the left and right brake pedals are set to the traveling regulation mode U. That is, when the lock sensor 38a detects a state in which the connection release operation of the left and right brake pedals is locked, the travel control unit 43 releases the travel regulation mode U and detects the main shift lever 17. The solenoid shaft 23 is automatically rotated to a position based on the value.

When the trunnion shaft 23 is automatically rotated at the same time as the traveling regulation mode U is released, if the rotation speed is set to be slower than when rotating during normal work, the trunnion shaft 23 travels slowly during traveling. Can be started to prevent a sudden start.

Although the drawing is omitted, in a tractor provided with a one-sided brake check mechanism, a brake cylinder is provided to push the left and right brake arms driven by a solenoid valve, and the left and right brakes are automatically applied by the brake cylinder in response to a certain handle operation. Provide an auto-brake mechanism to operate the vehicle. Then, by configuring the auto brake to operate only when the disconnection release pedal of the one-brake check mechanism is depressed to the release position, it is easy for the operator to apply the auto brake only when he / she wants to apply the auto brake. You can choose. In the past, it was necessary to select the on / off of the auto brake with a work dial or the like, and it was difficult to arbitrarily select the on / off of the auto brake during work, but according to this example, the on / off of the auto brake is as described above. Easy to choose.

In the above configuration, if an auxiliary transmission sensor is provided and the autobrake does not operate even when the disconnection pedal is depressed when the auxiliary transmission speed is high, it is possible to prevent the autobrake from accidentally operating during traveling.

Further, in the above configuration, when an axle rotation speed detection sensor is provided and a rotation speed above a certain level is detected, the autobrake does not operate even when the decoupling pedal is depressed, or the auxiliary shift and the HST trunnion opening degree are detected. However, if the calculated vehicle speed is above a certain level, the same effect can be obtained by configuring the autobrake not to operate.

As shown in FIGS. 15 to 16, the guide groove 55 of the lock lever 37 (see FIG. 8) of the brake pedal is installed on the resin cover 56, and the cover 56 is provided in order to prevent the lever 37 from directly hitting the resin cover 56. The bosses 57 are provided at four locations, and the iron plate guides are fixed to them with speed nuts. The lock lever moves downward along the guide groove 55 to lock, and conversely moves upward and then moves to the right to unlock.

In the example shown in FIGS. 17 and 18, in the configuration of the lock lever 37, a rotating fulcrum portion Q is installed on the lock lever, and a torque spring 57 is provided at the fulcrum portion so that a force is applied to the lever in one direction. It is configured in. Note that 58 is a stopper that regulates when manually operated.

In this embodiment, an agricultural tractor is used as an example of a work vehicle, but the present invention is not limited to this, and for example, a riding lawn mower for cutting grass grass, a riding management machine for spraying pesticides, a rice transplanter for planting seedlings, and the like may be used.

E engine 10 Hydrostatic continuously variable transmission (HST)
13L Left Brake Pedal 13R Right Brake Pedal 17 Main Shift Lever 18 Sub Shift Lever 20 Hydraulic Pump 21 Hydraulic Motor 23 Tranion Shaft 24 Operating Cylinder 28 Sub Transit Device 29 Tranion Shaft Operation Detection Means (Main Shift Sensor)
31 Sub-transmission operation detection means (sub-transmission sensor)
33 Brake pedal connection unit 34 Connection operation tool 37 Brake connection operation Lock means 38a Lock sensor 38b Connection sensor 43 Travel control unit 44 Engine control unit 50 Brake pedal sensor D Road travel mode U Travel regulation mode W Work travel mode

Claims (1)

With the engine
A hydrostatic continuously variable transmission that shifts and transmits the rotational power of the engine,
A traveling control unit that controls an operation cylinder that shifts gears by operating the trunnion shaft of the hydrostatic continuously variable transmission.
Left and right braking devices that brake the left and right drive wheels, respectively,
The left and right brake pedals that operate the left and right braking devices, respectively,
A brake pedal connecting part that connects the left and right brake pedals,
A connection sensor that detects whether the brake pedal connection portion is in a connected state or a non-connected state, and
It is equipped with a brake pedal sensor that detects the operation of either the left or right brake pedal.
When the connection sensor detects the connection state and the brake pedal sensor detects the operation of the left or right brake pedal, the travel control unit decelerates and controls the operation cylinder based on the amount of depression of the brake pedal. A work vehicle characterized by that.

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